The present invention relates to an output buffer circuit, and more particularly, to an output buffer whose output impedance can be changed.
As structure for a large scale integrations (LSls) becomes smaller and smaller, the quality of the LSI may become uneven. This creates a problem because there is a difference in impedance between a one output buffer and another output buffer even in the same LSI. For example, the difference in the impedance between output buffers becomes about +/-30 percent. The difference in the impedance between output buffers produces signal reflection, which deteriorates the performance of the LSI.